Piezoceramic material

ABSTRACT

A piezoceramic material comprising PbTiO 3 , PbZrO 3 , PbB&#39; 1- α  B&#34;.sub.α O 3 , and PbB&#39;&#34; 1- α B.sub.α IV  O 3 , wherein B&#39; is selected from the group consisting of Nb 5+ , W 6+  ; B&#34; is selected from the group consisting of Zn 2+ , Mg 2+ , Co 2+ , Mn 2+ , Ni 2+  ; B&#39;&#34; is selected from the group consisting of Nb 5+ , W 6+  ; B IV  is selected from the group consisting of Zn 2+ , Mg 2+ , Co 2+ , Ni 2+  ; α=1/2 for W 6+  and 1/3 for Nb 5+ , with B&#39; and B&#34;&#39; being equal to Nb 5+ , and B&#34; being equal to Ni 2+ , B IV  is neither equal to Zn 2+   nor to Mn 2+  ; with B&#39; and B&#39;&#34; being equal to Nb 5+ , B&#34;  being equal to Mg 2+ , B IV  is not equal to Mn 2+ , and the content of the above components being as follows, molar percent: 
     
         ______________________________________                                    
 
    
     PbTiO 3                                                                
        30.0 to 52.5                                                      
                   PbB 1- α &#39; B.sub.α &#34;O 3              
                                   1.5 to 28.4                            
PbZrO 3                                                                
        25.0 to 47.6                                                      
                   PbB 1- α &#39;&#34; B.sub.α IV  O 3       
                                   2.3 to 29.4                            
______________________________________

This is a continuation of application Ser. No. 653,886, filed Jan. 30, 1976 which in turn is a Rule 60 continuation of U.S. Ser. No. 341,953, filed Mar. 16, 1973, both now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to materials useful in electronics and, more specifically, to piezoceramic materials.

The materials are used in acoustics, hydroacoustics, ultrasonic delay lines, and filter technology.

It is known that the highest piezoactivity is revealed by compositions pertaining to morphotropic regions of binary and ternary systems of solid solutions. As the number of components in a system increases, the dimension of the morphotropic region is increased and the range of compositions having parameters of extreme values is broadened.

In the prior art piezoceramic materials comprising ternary systems of PbTiO₃ -PbZrO₃ -PbB'₁₋α B".sub.α O₃, wherein:

B' is Nb⁵⁺, W⁶⁺ ;

B" is Zn²⁺, Mg²⁺, Co²⁺, Mn²⁺, Ni²⁺ ;

α is equal to 1/2 for W⁶⁺, and 1/3 for Nb⁵⁺, with

the compositions pertaining to the morphotropic region, have the parameters shown in Table 1.

It follows from Table 1 that for many systems the values of the dielectric constant, the electromechanical force factor, and the mechanical Q-factor are insufficiently high, while the dielectric losses known for certain systems are excessively high.

Furthermore, in some cases, e.g. in the production of high frequency ultrasonic transducers, it is necessary to employ materials possessing low values of the dielectric constant ε^(T) ₃₃ at a relatively high electromechanical force factor K_(p). The prior art materials (see for example Table 1), however, do not comply with this requirement.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide highly efficient materials possessing high values of the dielectric constant ε^(T) ₃₃ , the electromechanical force factor K_(p), and the piezoelectric modulus d₃₁ which may be useful in acoustics, seismoscopes, and in other applications where piezomaterials should reveal maximum piezoelectric properties.

It is another object of the present invention to provide materials possessing low dielectric losses tgδ in weak (E=10 to 30 V/cm), but intense (E=2 kV/cm) fields and a high quality factor with sufficiently high piezoelectric parameters (K_(p) and d₃₁). Such materials may be useful in hydroacoustics.

Still another object of the present invention is to provide materials possessing low values of the dielectric constant at a relatively high electromechanical force factor. Such materials may be useful in ultrasonic delay lines (UDL). Another object of the present invention, is to provide materials possessing a high mechanical Q-factor and a good stability at the resonance frequency. Such materials may be useful in filter technology.

                                      TABLE 1                                      __________________________________________________________________________                                 Electrophysical parameters                                                           Electromecha-                                                                          Mechanical                                                                           Dielectric                        PbB'.sub.1-α  B.sub.α.sup." O.sub.3                                                         Dielectric                                                                           nical force                                                                            quality                                                                              losses (in                        in ternary               constant                                                                             factor  factor                                                                               weak field)                    No.                                                                               system   Reference       ε.sub.33.sup.T                                                               K.sub.p Q     tg δ.                    __________________________________________________________________________                                                     °K.                     1  PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                         Japanese Patent No. 9,511/72                                                                   1,570-3,120                                                                          0.568-0.714                                                                            --    --                             2  PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                         H.Ouchi.J. Am. Ceram.                                                                          2,137 0.638   65    1.87                                       Soc. 51, 169 (1968)                                                3  PbNb.sub.170 CO.sub.1/3 O.sub.3                                                         Japanese Patent No. 13,146/70                                                                  1,360-2,030                                                                          0.64-0.73                                                                              305-420                                                                              --                             4  PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                         Japanese Patent No. 35,472/71                                                                  630-1,000                                                                            0.35-0.61                                                                              1,900-2,030                                                                          1.1-2.3                        5  PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                         Japanese Patent No. 45-14,465                                                                  720-3,200                                                                            0.4-0.61                                                                               95-161                                                                               --                             6  Pb W.sub.1/2 Zn.sub.1/2 O.sub.3                                                         French Patent No. 1,554,730                                                                    1,500-2,500                                                                          0.52-0.59                                                                              72-80 --                             7  Pb W.sub.1/2 Mg.sub.1/2 O.sub.3                                                         French Patent No. 1,551,976                                                                    --    0.25-0.5                                                                               295-300                                                                              --                             __________________________________________________________________________     1   2        3              4     5       6     7                              __________________________________________________________________________     8  PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                          French Patent No. 1,554,730                                                                    1,090-1,800                                                                          0,4-0.6 15-80 --                             9  PbW.sub.1/2 CO.sub.1/2 O.sub.3                                                          Japanese Patent No. 46-2,354                                                                   1,130-1,980                                                                          0,42-0.63                                                                              --    --                             __________________________________________________________________________

These and other objects of the present invention are accomplished by providing a piezoceramic material comprising PbTiO₃, PbZrO₃, and PbB'₁₋α B".sub.α O₃, wherein B'=Nb⁵⁺, W⁶⁺ ; B"=Zn²⁺, Mg²⁺, Co²⁺, Mn²⁺, Ni²⁺ ; α=1/2 for W⁶⁺, and 1/3 for Nb⁵⁺, and which material according to the present invention comprises a fourth component PbB'"₁₋α B^(IV).sub.α O₃, wherein B'" is Nb⁵⁺, W⁶⁺ ; B^(IV) =Zn²⁺, Mg²⁺, Co²⁺, Mn²⁺, Ni; α=1/2 for W⁶⁺, and 1/3 for Nb⁵⁺ ; with B' and B'"=Nb⁵⁺, B"=Ni²⁺, B^(IV) is neither Zn²⁺ nor Mn²⁺ ; with B' and B'"=Nb⁵⁺, B"=Mg²⁺, B^(IV) is not Mn²⁺, the components being contained in the material in the following amounts, in molar percent:

PbTiO₃ =30.0 to 52.5

PbZrO₃ =25.0to 47.6

PbB'₁₋α B".sub.α O₃ =1.5 to 28.4

PbB'"₁₋α B^(IV).sub.α O₃ =2.3 to 29.4

Within the above limits the following are preferred:

PbTiO₃ =37.5 to 42.5

PbZrO₃ =33.0 to 42.0

PbB'₁₋α B".sub.α O₃ =5.0 to 15.0

PbB'"₁₋α B^(IV).sub.α O₃ =5.0 to 15.0

The following is a list of piezoceramic materials referred to hereinafter as systems, the content of the components being given in molar percent:

    ______________________________________                                         System 1                                                                       ______________________________________                                         PbTiO.sub.3         32.5 to 45.0                                               PbZrO.sub.3         26.0 to 44.5                                               PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                    1.9 to 18.6   (1)                                          PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                    2.5 to 21.8                                                ______________________________________                                    

The material may also contain, as a modifying oxide, from 3.6 to 3.9 mol.% of MnO₂ or from 0.83 to 0.86 mol.% of CoO.

    ______________________________________                                         System 2                                                                       ______________________________________                                         PbTiO.sub.3         35.0 to 42.5                                               PbZrO.sub.3         27.0 to 39.3                                               PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                    2.0 to 17.8   (2)                                          PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                    2.9 to 26.5                                                ______________________________________                                    

This material may additionally contain, as a modifying oxide, from 3.5 to 3.7 mol.% of MnO₂ or 2.03 mol.% of Fe₂ O₃.

    ______________________________________                                         System 3                                                                       ______________________________________                                         PbTiO.sub.3         35.0 to 45.0                                               PbZrO.sub.3         25 to 42.55                                                PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                    2.4 to 21.6   (3)                                          PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                    2.8 to 27.6                                                ______________________________________                                    

This material may also contain, as a modifying oxide, from 1.9 to 3.8 mol.% of Mno₂.

    ______________________________________                                         System 4                                                                       ______________________________________                                         PbTiO.sub.3         35.0 to 47.5                                               PbZrO.sub.3         36.22 to 44.94                                                                               (4)                                          PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                    1.73 to 15.15                                              PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                    4.3 to 12.29                                               ______________________________________                                    

    ______________________________________                                         System 5                                                                       ______________________________________                                         PbTiO.sub.3         37.5 to 45.0                                               PbZrO.sub.3         34.7 to 44.6                                               PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                    3.5 to 21.4   (5)                                          PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                    4.3 to 10.5                                                ______________________________________                                    

    ______________________________________                                         System 6                                                                       ______________________________________                                         PbTiO.sub.3         30.0 to 42.5                                               PbZrO.sub.3         23.1 to 44.3  (6)                                          PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                    8.3 to 22.7                                                PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                    4.3 to 29.4                                                ______________________________________                                    

The material may also contain, as a modifying oxide, from 0.76 to 3.8 mol.% of MnO₂.

    ______________________________________                                         System 7                                                                       ______________________________________                                         PbTiO.sub.3         30.0 to 45.0                                               PbZrO.sub.3         25.4 to 47.6  (7)                                          PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                    2.3 to 22.7                                                PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                    4.1 to 29.4                                                ______________________________________                                    

The material may also contain from 1.9 to 3.8 mol.% of MnO₂ as a modifying agent.

    ______________________________________                                         System 8                                                                       ______________________________________                                         PbTiO.sub.3         32.5 to 42.5                                               PbZrO.sub.3         32.8 to 42.8  (8)                                          PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                     6.1 to 17.8                                                PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                    5.7 to 15.0                                                ______________________________________                                    

The material may also contain from 0.76 to 1.9 mol.% of MnO₂ as a modifying oxide.

    ______________________________________                                         System 9                                                                       ______________________________________                                         PbTiO.sub.3         32.5 to 45.0                                               PbZrO.sub.3         30.0 to 46.4  (9)                                          PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                     6.1 to 16.2                                                PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                    8.0 to 21.8                                                ______________________________________                                    

The material may additionally contain, as a modifying oxide, from 0.77 to 3.8 mol.% of MnO₂.

    ______________________________________                                         System 10                                                                      ______________________________________                                         PbTiO.sub.3         32.5 to 45.0                                               PbZrO.sub.3         33.4 to 42.8  (10)                                         PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                     6.1 to 15.0                                                PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                    5.4 to 15.0                                                ______________________________________                                    

It is advisable to incorporate into the material, as a modifying oxide, from 0.76 to 3.8 mol.% of MnO₂.

    ______________________________________                                         System 11                                                                      ______________________________________                                         PbTiO.sub.3      35.0 to 45.0                                                  PbZrO.sub.3      30.6 to 44.5  (11)                                            PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  6.1 to 14.0                                                   PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                 6.9 to 17.2                                                   ______________________________________                                    

    ______________________________________                                         System 12                                                                      ______________________________________                                         PbTiO.sub.3      35.0 to 45.0                                                  PbZrO.sub.3      32.3 to 44.6  (12)                                            PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  6.1 to 16.2                                                   PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                 4.1 to 11.7                                                   ______________________________________                                    

As a modifying oxide, there may be added to this material from 0.76 to 1.9 mol.% of MnO₂.

    ______________________________________                                         System 13                                                                      ______________________________________                                         PbTiO.sub.3      35.0 to 52.5                                                  PbZrO.sub.3      33.58 to 44.2                                                 PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  4.48 to 11.37 (13)                                            PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                 6.1 to 16.19                                                  ______________________________________                                    

    ______________________________________                                         System 14                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 42.5                                                  PbZrO.sub.3      32.8 to 39.4                                                  PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  6.4 to 16.2   (14)                                            PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                  6.4 to 15.5                                                   ______________________________________                                    

    ______________________________________                                         System 15                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 45.0                                                  PbZrO.sub.3      34.7 to 44.9                                                  PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  4.3 to 11.4   (15)                                            PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                 5.7 to 14.4                                                   ______________________________________                                    

This material may additionally contain, as a modifying oxide, from 0.76 to 1.9 mol.% of MnO₂.

    ______________________________________                                         System 16                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 42.5                                                  PbZrO.sub.3      30.0 to 42.0                                                  PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  1.5 to 13.5   (16)                                            PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                 2.3 to 22.0                                                   ______________________________________                                    

The material may contain, as a modifying oxide from 0.76 to 3.8 mol.% of MnO₂.

    ______________________________________                                         System 17                                                                      ______________________________________                                         PbTiO.sub.3      35.0 to 42.5                                                  PbZrO.sub.3      22.9 to 45.6  (17)                                            PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  5.32 to 14.1                                                  PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                 3.6 to 21.8                                                   ______________________________________                                    

    ______________________________________                                         System 18                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 45.0                                                  PbZrO.sub.3      36.8 to 45.3  (18)                                            PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  5.12 to 13.54                                                 PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                 4.48 to 11.37                                                 ______________________________________                                    

    ______________________________________                                         System 19                                                                      ______________________________________                                         PbTiO.sub.3      32.5 to 45.0                                                  PbZrO.sub.3      38.4 to 42.5                                                  PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                 4.1 to 28.4   (19)                                            PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  5.8 to 13.6                                                   ______________________________________                                    

This material may contain, as a modifying oxide, from 0.76 to 1.9 mol.% of MnO₂.

    ______________________________________                                         System 20                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 45.0                                                  PbZrO.sub.3      32.5 to 42.0                                                  PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  6.7 to 16.2   (20)                                            PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  5.1 to 13.6                                                   ______________________________________                                    

    ______________________________________                                         System 21                                                                      ______________________________________                                         PbTiO.sub.3      35.0 to 45.0                                                  PbZrO.sub.3      32.2 to 44.7  (21)                                            PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  4.1 to 10.0                                                   PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                                 8.1 to 21.8                                                   ______________________________________                                    

    ______________________________________                                         System 22                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 45.0                                                  PbZrO.sub.3      36.2 to 42.8                                                  PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                  6.1 to 16.0   (22)                                            PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  4.3 to 12.8                                                   ______________________________________                                    

    ______________________________________                                         System 23                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 45.0                                                  PbZrO.sub.3      35.7 to 43.9                                                  PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  4.1 to 11.0   (23)                                            PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  5.4 to 13.0                                                   ______________________________________                                    

    ______________________________________                                         System 24                                                                      ______________________________________                                         PbTiO.sub.3      30.0 to 45.0                                                  PbZrO.sub.3      25.0 to 47.6                                                  PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                  1.5 to 28.4   (24)                                            PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                 2.3 to 29.4                                                   ______________________________________                                    

    ______________________________________                                         System 25                                                                      ______________________________________                                         PbTiO.sub.3      30.0 to 45.0                                                  PbZrO.sub.3      25.0 to 47.6                                                  PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  1.5 to 28.4   (25)                                            PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                                 2.3 to 29.4                                                   ______________________________________                                    

    ______________________________________                                         System 26                                                                      ______________________________________                                         PbTiO.sub.3      30.0 to 45.0                                                  PbZrO.sub.3      25.0 to 47.6                                                  PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                  1.5 to 28.4   (26)                                            PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                 2.3 to 29.4                                                   ______________________________________                                    

    ______________________________________                                         System 27                                                                      ______________________________________                                         PbTiO.sub.3      30.0 to 45.0                                                  PbZrO.sub.3      25.0 to 47.6                                                  PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                                 1.5 to 28.4   (27)                                            PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  2.3 to 29.4                                                   ______________________________________                                    

    ______________________________________                                         System 28                                                                      ______________________________________                                         PbTiO.sub.3      30.0 to 45.0                                                  PbZrO.sub.3      25.0 to 47.6                                                  PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                  1.5 to 28.4   (28)                                            PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                 2.3 to 29.4                                                   ______________________________________                                    

    ______________________________________                                         System 29                                                                      ______________________________________                                         PbTiO.sub.3      37.5 to 42.5                                                  PbZrO.sub.3      40.5 to 37.26                                                 PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                                  5.34 to 5.82  (29)                                            PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                  14.9 to 16.18                                                 ______________________________________                                    

    ______________________________________                                         System 30.                                                                     ______________________________________                                         PbTiO.sub.3       37.5 to 45.0                                                 PbZrO.sub.3       36.85 to 46.69                                               PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                   4.12 to 10.94   (30)                                         PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                  4.30 to 10.92                                                ______________________________________                                    

    ______________________________________                                         System 31                                                                      ______________________________________                                         PbTiO.sub.3       37.5 to 45.0                                                 PbZrO.sub.3       36.25 to 42.42                                               PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                   6.1 to 16.38    (31)                                         PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                                                                  4.68 to 11.37                                                ______________________________________                                    

    ______________________________________                                         System 32                                                                      ______________________________________                                         PbTiO.sub.3       35.0 to 42.5                                                 PbZrO.sub.3       38.29 to 43.29                                               PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                                   14.9 to 16.83   (32)                                         PbW.sub.1/2 Co.sub.1/2 O.sub.3                                                                   4.31 to 4.88                                                 ______________________________________                                    

    ______________________________________                                         System 33                                                                      ______________________________________                                         PbTiO.sub.3       35.0 to 42.5                                                 PbZrO.sub.3       28.18 to 35.82                                               PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                                   12.9 to 15.54   (33)                                         PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                                  8.28 to 18.56                                                ______________________________________                                    

the majority of the above Systems possess high piezoelectric parameters.

Some parameters of the best compositions among these highly efficient Systems are shown in Table 2 hereinbelow.

Therefore, the best compositions of the highly efficient Systems have:

ε₃₃ ^(T) =2,159 to 4,441

K_(p) =0.605 to 0.722

d₃₁ =(5.42 to 9.38).10⁻⁶ CGSE units.

These materials may find application in acoustics, seisomoscopes, and in other utilities where piezomaterials should reveal maximal piezoelectric properties.

Cobalt-containing Systems possess, in addition to the high piezoelectric characteristics thereof, an improved value of mechanical quality factor Q=260 to 600.

In the manganese-containing Systems, the majority of compositions have low dielectric losses in weak and intense fields: tgδ (weak field)=0.2 to 1.0%; tgδ (intense field, E=2 kv/cm)=1.0 to 3.4% and a high mechanical quality Q=400 to 2,500 at sufficiently high piezoelectric parameters; this is very valuable for materials employed in hydroacoustics. Parameters of some compositions of these Systems are shown in Table 3 below.

                                      TABLE 2                                      __________________________________________________________________________     Sy-                                                                            stem                          Electrophysical                                  No.                                                                               Composition, mol. %        parameters                                       1  2    3    4       5        6  7  8                                                                              d.sub.31 . 10.sup.6                           PbTiO.sub.3                                                                         PbZrO.sub.3                                                                         PbB'.sub.1-α B".sub.α O.sub.3                                              PbB"'.sub.1-α B".sub.α O.sub.3                                              ε.sub.33.sup.T                                                            Kp CGSE                                       __________________________________________________________________________                  PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                                                        PBNB.sub.2/3 Mg.sub.1/3 O.sub.3                                                               units                                       1 42.50                                                                               40.7 4.3     12.5     2.260                                                                             0.67                                                                              6.6                                                     PBNB.sub.2/3 Mg.sub.1/3 O.sub.3                                                        PBNB.sub.2/3 Co.sub.1/3 O.sub.3                            3 42.50                                                                               42.55                                                                               7.18    7.77     2.210                                                                             0.67                                                                              6.03                                                    PBNB.sub.2/3 Mg.sub.1/3 O.sub.3                                                        PBNB.sub.2/3 Ni.sub.1/3 O.sub.3                            6 42.50                                                                               39.16                                                                               8.29    10.05    3.130                                                                             0.677                                                                             7.8                                                     PBNB.sub.2/3 Ni.sub.1/3 O.sub.3                                                        PBNB.sub.2/3 Co.sub.1/3 O.sub.3                            7 35.00                                                                               28.34                                                                                27.30  9.36     2.699                                                                             0.656                                                                             6.44                                                    PBW.sub.1/2 Zn.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                            8 40.00                                                                               39.48                                                                               6.66    13.86    2.555                                                                             0.658                                                                             6.72                                                    PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                           10 40.00                                                                               39.48                                                                               6.66    13.86    2.762                                                                             0.703                                                                             7.65                                                    PBW.sub.1/2 Zn.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Co.sub.1/3 O.sub.3                            9 42.50                                                                               42.66                                                                               6.38    8.46     2.159                                                                             0.65                                                                              5.67                                                    PBW.sub.1/2 Ni.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                           15 42.50                                                                               39.73                                                                               4.48    13.29    2.480                                                                             0.613                                                                             5.92                                                    PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Co.sub.1/3 O.sub.3                           11 42.50                                                                               37.37                                                                                12.88  7.25     2.973                                                                             0.618                                                                             6.23                                                    PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Ni.sub.1/3 O.sub.3                           12 40.00                                                                               36.60                                                                                13.10  10.30    3.166                                                                             0.652                                                                             7.33                                                    PBW.sub.1/2 Ng.sub.1/3 O.sub.3                                                         PBW.sub.1/2 Zn.sub.1/2 O.sub.3                            14 40.00                                                                               37.80                                                                               6.66    15.54    2.634                                                                             0.675                                                                             7.06                                                    PBNB.sub.2/3 Mg.sub.1/3 O.sub.3                                                        PBW.sub.1/2 Ni.sub.1/2 O.sub.3                            16 40.00                                                                               35.40                                                                                14.76  9.84     3.860                                                                             0.722                                                                             9.38                                                    PBW.sub.1/2 Ni.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Co.sub.1/3 O.sub.3                           17 40.00                                                                               34.26                                                                               5.58    20.16    2.730                                                                             0.645                                                                             6.42                                                    PBNB.sub.2/3 Ni.sub.1/3 O.sub.3                                                        PBW.sub.1/2 Ni.sub.1/2 O.sub.3                            19 35.00                                                                               31.65                                                                                27.30  6.05     4.441                                                                             0.608                                                                             7.66                                                    PBNB.sub.2/3 Ni.sub.1/3 O.sub.3                                                        PBW.sub.1/2 Ni.sub.1/2 O.sub.3                               37.50                                                                               30.44                                                                                26.25  5.81     2.360                                                                             0.655                                                                             6.14                                                    PBW.sub.1/2 Co.sub.1/2 O.sub.3                                                         PBNB.sub.2/3 Co.sub.1/3 O.sub.3                           21 37.50                                                                               35.00                                                                               9.62    17.88    3.368                                                                             0.622                                                                             6.65                                                    PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                         PBW.sub.1/2 Co.sub.1/2 O.sub.3                            22 42.50                                                                               38.29                                                                                14.89  4.32     2.390                                                                             0.605                                                                             5.42                                                    PBW.sub.1/2 Ni.sub.1/2 O.sub.3                                                         PBW.sub.1/2 Co.sub.1/2 O.sub.3                            23 42.50                                                                               4071 4.31    12.48    2.387                                                                             0.633                                                                             5.84                                       __________________________________________________________________________

Some of the materials of the present invention (see, for example, Table 4) possess low values of the dielectric constant at a relatively high electromechanical force factor, which makes it possible for them to be employed in ultrasonic delay lines (UDL).

Some of the compositions (see, for example, Table 5 below show a rather high mechanical Q-factor at a comparatively high electromechanical factor K_(p).

Parameters of some of such compositions are given in Table 5.

Some compositions have a good stability of the resonance frequency f_(r) within a temperature range of from -40° to +80° C. (Table 6) in addition to their sufficiently high mechanical Q-factor and high electromechanical force factor values, which enables the use thereof in filter technology.

Modification of the piezoceramic material according to the present invention makes it possible, in some cases, to produce even more efficient dielectric and piezoceramic parameters.

Thus, the introduction into some systems of from 0.76 to 3.9 mol. % of MnO₂ or from 0.83 to 0.86 mol. % of CoO substantially reduces the dielectric losses in intense fields, improves the mechanical Q-factor, makes it possible to produce compositions with low dielectric losses with relatively high piezoelectric parameters K_(p) and d₃₁, and results in a combination of a low dielectric constant with a relatively high electromechanical force factor, which is very important in ultrasonic delay lines.

Data illustrating dielectric and piezoelectric characteristics of pure tested and best modified compositions of some systems of the present invention are given in Table 7.

                                      TABLE 3                                      __________________________________________________________________________                                    Electrophysical                                                                Parameters                                      Sys-                                                                              Composition, mol. %         tgδ, %  d.sub.31 . 10.sup.6               tem          PbB'.sub.1-α                                                                      PbB"'.sub.1-α                                                                     weak                                                                               E=2       units                             No.                                                                               PbTiO.sub.3                                                                         PbZrO.sub.3                                                                         B".sub.α O.sub.3                                                                  B".sub.α O.sub.3                                                                  field                                                                              kv/cm                                                                              Kp ε.sub.33.sup.T                                                            CGSE Q                            __________________________________________________________________________                  PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                                                         PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                           4 42.5 39.73                                                                               13.29    4.48     0.24                                                                               1.0 0.577                                                                             1.310                                                                             3.65 1,000                                     PBNB.sub.2/3 Co.sub.1/3 O.sub.3                                                         PBNB.sub.2/3 Mn.sub.1/2 O.sub.3                           5 42.5 44.56                                                                               8.45     4.49     0.28                                                                               1.5 0.646                                                                             1.340                                                                             4.34 1,000                                     PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                          PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                          13 45.00                                                                               42.90                                                                               7.27     4.83     0.35                                                                               2.0 0.662                                                                             1.970                                                                             5.70 900                                       PBW.sub.1/2 Mg.sub.1/2 O.sub.3                                                          PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                          13 43.75                                                                               37.30                                                                               14.56    4.39     0.19                                                                               2.9 0.647                                                                             2.550                                                                             6.28 770                                       PBW.sub.1/2 Ni.sub.1/2 O.sub.3                                                          PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                          18 42.5 40.54                                                                               12.48    4.48     0.34                                                                               3.1 0.639                                                                             2.270                                                                             68                                __________________________________________________________________________

                                      TABLE 4                                      __________________________________________________________________________     Syst-                         Electrophysical                                  em Composition, mol. %        parameters                                       No.                                                                               PbTiO.sub.3                                                                         PbZiO.sub.3                                                                         PbB.sub.1-α.sup.I B.sub.α.sup.II O.sub.3                                   PbB.sub.1-α.sup.III B.sub.α.sup.IV                                 O.sub.3  ε.sub.33.sup.T                                                             Kp                                           __________________________________________________________________________     PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                 13 42.50                                                                               36.86                                                                               19.14   1.5      434 0.509                                        PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.1/3 Mn.sub.1/3 O.sub.3                 18 40.0 43.5 5.58    10.92    500 0.518                                        PBNB.sub.2/3 Co.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                5  40.0 45.72                                                                               3.78    10.5     510 0.532                                        PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                 13 45.00                                                                               30.26                                                                               14.84   9.9      518 0.536                                        PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3                 10  42.50                                                                              46.00                                                                               5.75    5.75     845 0.610                                        __________________________________________________________________________

                                      TABLE 5                                      __________________________________________________________________________     Sys-                          Electrophysical                                  tem                                                                               Composition, mol. %        parameters                                       No.                                                                               PbTiO.sub.3                                                                         PbZiO.sub.3                                                                         PbB.sub.1-α.sup.I B.sub.α.sup.II O.sub.3                                   PbB.sub.1-α.sup.III B.sub.α.sup.IV                                 O.sub.3  Q   Kp                                           __________________________________________________________________________     PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                4  35.0 40.95                                                                               15.15   8.9      2,120                                                                              0.49                                         PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                4  37.5 43.18                                                                               14.44   4.88     1,910                                                                              0.52                                         PBNB.sub.2/3 Co.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                5  42.5 38.58                                                                               8.45    10.47    2,370                                                                              0.52                                         PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                 18 37.5 45.31                                                                               5.82    11.37    2,360                                                                              0.52                                         PBW.sub.1/2 Co.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3                 30 42.50                                                                               38.52                                                                               9.1     9.88     2,440                                                                              0.51                                         __________________________________________________________________________

                                      TABLE 6                                      __________________________________________________________________________                                Electrophysical parameters                          Sys- tem No.                                                                       PbTiO.sub.3PbZrO.sub.3PbB.sup.I  .sub.1-αB .sub.α.sup.IIO.        sub.3PbB.sup.III  .sub.1-αB α.sup.IVO.sub.3Composition,            mol. %                   Q   K.sub.p                                                                            ##STR1##                                   __________________________________________________________________________                  PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                            13 52.5 33.58                                                                               5.28    8.64  1,150                                                                              0.33                                                                               <0.15                                                    PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                             5 45.0 38.5 7.26    9.24  1,300                                                                              0.44                                                                               <0.2                                                     PbNb.sub.2/3 Co.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                             5 45.0 36.9 8.08   10.02  1,480                                                                              0.43                                                                               <0.2                                                     PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mn.sub.1/3 O.sub.3                             4 47.5 38.48                                                                               1.73   12.29  890 0.46                                                                               <0.2                                        __________________________________________________________________________

                                      TABLE 7                                      __________________________________________________________________________                                     Electrophysical parameters                     Composition, mol. %                 tgδ, %                               Sys- tem No.                                                                       PbTiO.sub.3                                                                         PbZrO.sub.3                                                                         PbB.sup.I  .sub.1-αB .sub.α.sup.IIO.sub.3                                 PbB.sup.III  .sub.1-αB α.sup.IVO.sub.3                                   Modify- ing agent                                                                    ε.sup.T .sub.33                                                            fieldin weak                                                                        ##STR2##                                                                              K.sub.p                                                                           d.sub.31 ·                                                            10.sup.6 units                                                                         QSE                1  2    3    4      5      6    7   8    9      10  11     12                  __________________________________________________________________________                  PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                            1  32.5 40.7 2.3    24.5   --   820 2.83 34.0   0.456                                                                              2.23   130                                            MnO.sub.2                                              "    "    "      "      3.7  400 0.3  1.1    0.4 1.23   2,530                            PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                               35.0 42.2 15.0   7.8    --   860 2.6  28.3   0.508                                                                              2.67   110                                            MnO.sub.2                                              "    "    "      "      3.9  420 0.22 1.25   0.446                                                                              1.45   2,280                            PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                               35.0 52.7 5,4    6.9    --   680 2,96 27.0   0.391                                                                              1.75   136                                            MnO.sub.2                                              "    "    "      "      3.6  360 0,24 1.3    0.397                                                                              1.13   1.900                            PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                               40,0 48.6 5,0    6.4    --   797 2,82 --     0.554                                                                              2.86   102                                            MnO.sub.2                                              "    "    "      "      3.7  405 0,3  1.6    0.478                                                                              1.52   2.185                            PbNb.sub.2/3 Zn.sub.1/3 O.sub. 3                                                      PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                            "  40,0 38.9 13,9   7.2    --   1,970                                                                              2,4  11.8   0.643                                                                              5.58   77                                             CoO                                                    "    "    "      "      0.86 1,940                                                                              0,5  7.0    0.654                                                                              5.48   374                              PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O                                  2  40,0 40.8 8,3    10.9   --   880 1,03 15.9   0.512                                                                              2.9    266                                            MnO.sub.2                                              "    "    "      "      3.5  490 0,56 1.8    0.518                                                                              1.86   1.890                            PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            3  42.5 33.98                                                                               20.7   2.82   --   2,400                                                                              0.97 8.3    0.625                                                                              5.7    120                                            MnO.sub.2                                              "    "    "      "      1.9  2,000                                                                              0.27 2.8    0.66                                                                               5.58   760                              PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            "  35.0 38.42                                                                               23.4   3.18   --   760 1.3  21.1   0.542                                                                              2.545  155                                            MnO.sub.2                                           "  "    "    "      "      3.8  506 0.24 0.75   0.446                                                                              1.58   107                              PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 NiO.sub.3                                     6  35.0 28.34                                                                               9.36   27.3   --   3,740                                                                              1.8  15.0   0.642                                                                              7.67   67                                             MnO.sub.2                                              "    "    "      "      0.76 1,960                                                                              0.23 4.85   0.611                                                                              5.07   250                              PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                            "  37.5 42.56                                                                               9.0    10.94  --   755 2.2  38.5   0.582                                                                              2.7    130                                            MnO.sub.2                                           "  "    "    "      "      3.8  524 0.38 2.0    0.510                                                                              1.31   750                              PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            7  35.0 28.34                                                                               9.36   27.3   --   2,700                                                                              1.98 13.35  0.656                                                                              6.44   250                                            MnO.sub.2                                              "    "    "      "      1.9  1,240                                                                              0.57 1.4    0.576                                                                              3.55   6                      "         PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                            8  40.0 39.48                                                                               6.66   13.86  --   2,560                                                                              1.49 10.0   0.658                                                                              6.72   56                                             MnO.sub.2                                              "    "    "      "      1.9  1,690                                                                              0.5  1.3    0.595                                                                              4.41   620                              PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            9  40.0 33.18                                                                               6.66   20.16  --   2,130                                                                              2.26 13.5   0.64                                                                               5.53   280                                            MnO.sub.2                                              "    "    "      "      19.  1,620                                                                              0.5  2.0    0.555                                                                              4.1    650                              PbW.sub.1/2 Zn.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            "  37.5 37.31                                                                               16.8   9.01   --   720 1.08 11.8   0.53                                                                               2.45   276                                            MnO.sub.2                                           "  "    "    "      "      3.8  467 0.61 1.4    0.427                                                                              1.5    740                              PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                            10 40.0 39.48                                                                               6.66   13.86       2,60                                                                               1.35 15.0   0.703                                                                              7.65   67                                             MnO.sub.2                                                                      1.9  2,030                                                                              0.33 1.4    0.583                                                                              4.7    710                    "         PbW.sub.1/2 Mg.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                            12 40.0 39.96                                                                               15.54  4.5    --   3,320                                                                              1.44 15.8   0.628                                                                              6.95   110                                            MnO.sub.2                                              "    "    "      "      1.9  2,240                                                                              0.61 1.65   0.602                                                                              5.22   590                              PbW.sub.1/2 Ni.sub.1/2 O.sub.3                                                        PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                            15 42.5 39.73                                                                               4.48   13.29  --   2,480                                                                              1.2  9.4    0.613                                                                              5.89   83                                             MnO.sub.2                                              "    "    "      "      1.9  1,910                                                                              0.52 1.7    0.657                                                                              5.42                                    PbNb.sub.2/3 Ni.sub.1/3 O.sub.3                                                       PbW.sub.1/2 Ni.sub.1/2 O.sub.3                             19 40.0 36.6 11.46  11.94  --   3,010                                                                              1.48 12.0   0.637                                                                              6.73   89                                             MnO.sub.2                                              "    "    "      "      1.9  1,000                                                                              0.42 1.0    0.565                                                                              3.1    840                              PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbW.sub.1/2 Ni.sub.1/2 O.sub.3                             16 38.75                                                                               30.62                                                                               18.37  12.25  --   4,260                                                                              1.78 17.0   0.675                                                                              8.82   70                                             MnO.sub.2                                              "    "    "      "      0.76 2,580                                                                              0.29 5.0    0.651                                                                              6.36   218                              PbNb.sub.2/3 Mg.sub.1/3 O.sub.3                                                       PbW.sub.1/2 Ni.sub.1/2 O.sub.3                             "  38.75                                                                               30.62                                                                               18.37  12.25  --   4,260                                                                              1.77 17.0   0.675                                                                              8.82   70                                             MnO.sub.2                                              "    "    "      "      1.9  2,080                                                                              0.7  2.25   0.596                                                                              4.93   630                 __________________________________________________________________________

The introduction of 2.03 mol. % of Fe₂ O₃ enables the production of a material possessing lower dielectric losses in weak and strong fields at increased values of dielectric and piezoelectric parameters (Table 8).

The piezoceramic material of the present invention is prepared in the following manner.

The starting materials are employed in the form of oxides, carbonates and hydroxides of metals, for example:

PbCO₃

TiO₂

ZrO₂

Nb₂ O₅

WO₃

Mg(OH)₂

ZnO

MnCO₃

MnO₂

Co(OH)₂

Fe₂ O₃

The starting components of a particular composition are mixed in ball mills according to a "wet process" for a period of 10 hours, whereafter the material is synthesized twice. The synthesis is performed according to conventional ceramic technology in a protective atmosphere of PbO. The synthesis conditions are as follows: a temperature ranging from 750° to 850° C.; the duration of the first synthesis is 4 hours, the second synthesis lasts for 10 hours.

                                      TABLE 8                                      __________________________________________________________________________                                    Electrophysical parameters                                                         tgδ, %                                Sys- tem No.                                                                       PbTiO.sub.3PbZrO.sub.3PbB.sup.I  .sub.1-αB .sub.α.sup.IIO.        sub.3PbB.sup.III  .sub.1-αB .sub.α.sup.IVO.sub.3Composition        , mol. %                Modi- fying agent                                                                   ε.sup.T .sub.33                                                           in weak field                                                                       ##STR3##                                                                              K.sub.p                                                                            CGSE unitsd.sub.31                                                            · 10.sup.6,                                                                   Q                    __________________________________________________________________________                  PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            2  38.8 40.1 18.2   3.0    --  1,560                                                                              1.58                                                                               11.8   0.6 4.36   100                      "    "    "      "          Fe.sub.2 O.sub.3                                                           2.03                                                                               2,290                                                                              0.66                                                                               8.9    0.646                                                                              5.9    130                                PbNb.sub.2/3 Zn.sub.1/3 O.sub.3                                                       PbNb.sub.2/3 Co.sub.1/3 O.sub.3                            "  40.0 39.3 17.8   2.95   --  1,830                                                                              0.8 21.7   0.523                                                                              4.15   160                      "    "    "      "      Fe.sub.2 O.sub.3                                                                   1,920                                                                              0.48                                                                               6.4    0.576                                                                              4.59   180                                              2.03                                                __________________________________________________________________________

In order to obtain a high quality piezoceramic, the synthesized material is sintered using the hot-pressing method. The pressing conditions are as follows: temperature within the range of from 1,100° to 1,250° C., pressure of 200 kg/cm², and residence time of 40 min.

After the sintering step, the samples are ground.

In order to perform the polarization necessary to impart the piezoelectric properties to the ceramics, and to measure the electrophysical parameters, it is required that the samples be provided with electrodes. To this end, the samples are coated with a layer of silver paste and maintained at a temperature of 800° C.

The polarization is performed in a silicon oil comprising an organo-silicon liquid at a temperature of from 90° to 185° C. for 25 to 45 minutes in a field of 16.0 to 50 kv/cm intensity.

The samples are tested 24 hours after the polarization process.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For better understanding of the present invention the following examples illustrating the production of the piezoceramic material according to the present invention are given hereinbelow.

EXAMPLE 1

A piezoceramic material was prepared containing, in mol. %: PbTiO₃ -42.5; PbNb_(2/3) Zn_(1/3) O₃ --4.3; PbZrO₃ --40.7; PbNb_(2/3) Mg_(1/3) O₃ --12.5.

The starting materials for the above compositions were employed in the form of oxides, carbonates, and hydroxides of the metals: PbCO₃, TiO₂, ZrO₂, Nb₂ O₅, ZnO, Mg(OH)₂, and mixed in ball mills by a "wet process" for 10 hours. Then, the synthesis of the material was performed twice. The synthesis was effected according to a conventional ceramic technology in a protective PbO atmosphere. The synthesis conditions were as follows: temperature of 850° C., the duration of the first synthesis was 4 hours, the second synthesis duration was 10 hours. The material thus synthesized was subjected to sintering by the hot-pressing method. The hot-pressing conditions were as follows: temperature of 1,200° C., pressure of 200 kg/cm², and a residence time of 40 minutes. The polarization was performed in silicon oil at a temperature of 100° C. for 30 minutes in a field of 25.0 kV/cm intensity.

The resulting material of the above-mentioned composition had the following electrical characteristics:

ε^(T) ₃₃ =2,260; d₃₁ 6.6×10⁻⁶ units CGSE; K_(p) =0.67;

tgδ (in weak field) =1.5%.

EXAMPLE 2

Under conditions similar to those of Example 1, a piezoceramic material was prepared containing, in molar percent: PbTiO₃ --32.5; PbNb_(2/3) Zn_(1/3) O₃ --15.45; PbZrO₃ --32.4; PbNb_(2/3) Mg_(1/3) O₃ --19.65, and having the following characteristics: ε^(T) ₃₃ =2,500; d₃₁ =5.97×10⁻⁶ CGSE units; K_(p) =0.6; tg δ (in weak field)=1.6%; Q=83.

EXAMPLE 3

A piezoceramic material was prepared containing, in molar percent: PbTiO₃ --40.0; PbNb_(2/3) Zn_(1/3) O₃ --5.0; PbZrO₃ --48.6; PbNb_(2/3) Mg_(1/3) O₃ --6.4; and incorporating, as a modifying agent, 3.7 mol. % of MnO₂.

The starting components were taken in the following form: PbCO₃, TiO₂, ZrO₂, Nb₂ O₅, ZnO, Mg(OH)₂, MnO₂.

These components employed according to the above composition were mixed in ball mills by a "wet process" for 10 hours. Then, the material was synthesized twice. This synthesis was effected according to conventional ceramic technology in a protective PbO atmosphere. The synthesis conditions were as follows: temperature of 850° C., the first synthesis duration was 4 hours and the second synthesis duration was 10 hours. The sintering is performed by hot-pressing according to the following scheme: temperature 1,200° C., pressure of 200 kg/cm², residence time of 40 minutes. The polarization of samples was effected in silicon oil at a temperature of 100° C. for 30 minutes in a field of 30 kV/cm intensity. The resulting composition had the following electrophysical parameters: ε^(T) ₃₃ =405; d₃₁ =1.52×10⁻⁶ CGSE units, K_(p) =0.478; Q=2,185; tg ε (in weak field)=0.3%; at E=2 kV/cm tg ε=1.6%.

EXAMPLE 4

Under conditions similar to those of Example 3 a piezoceramic material was prepared containing, in molar percent: PbTiO₃ --42.5; PbNb_(2/3) Zn_(1/3) O₃ --4.3; PbZrO₃ --40.7; PbNb_(2/3) Mg_(1/3) O₃ --12.5; and incorporating, as a modifying oxide, 0.83 mol% of CoO. Co(OH)₂ was introduced as an additive in the stage of mixing all the starting components.

The electrophysical parameters of the material were as follows: ε^(T) ₃₃ =2,240; d₃₁ =6.75×10⁻⁶ CGSE units; K_(p) =0.69; tgδ (in weak field)=0.5%; at E=2 kV/cm tgδ=9.2%; Q=222. The following Examples from 5 to 75 are summarized in Table 9, wherein are shown the proportions of basic components, the concentration of the modifying agents incorporated, the conditions of synthesis, sintering, polarization an the values of the electrophysical parameters.

    TABLE 9       Conditions of Electrophysical parameters Sintering Polarization      tgδ, %    Synthesis T°C., T°C., t in   Example      Composition mol. % Modifying T°C., t, t, min min, E weak at E=      d.sub.31 . 10.sup.6 No. PbTiO.sub.3 PbZrO.sub.3 PbB.sup.I.sub.4-α      B.sup.II.sub.α O.sub.3 PbB.sup.III.sub.4-α       B.sup.IV.sub.α       O.sub.3 agent hours kg/cm.sup.2 kV/cm Σ.sub.33.sup.T field 2kV/cm K      p un.CGSE Q 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15           PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3            5 42.5 37.8 13.3 8.4 --  850 1200 100 1,740 0.9 -- 0.577 4.63 168           4+10 .sub.2/3  30        200 30 6 37.5 36.9 PBNB.sub.2/3 Zn.sub.1/3      O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3    10.3 15.3 -- " " " 1,000 1.1      -- 0.537 3.07 332 7 32.5 35.1 PBNB.sub.2/3 Zn.sub.1/3       O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3  850 1160 100      MnO.sub.2      4+10 .sub.2/3  30    14.1 18.3 3.7  200 30 582 0.98 1.6 0.44 1.7 2000 8      38.8 40.1 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 PBNB.sub.2/3 Co.sub.1/3      O.sub.3 Fe.sub.2 O.sub.3 850 1170 100        .sub.2/3  30    18.2 3.0      2.03 4+10 200 40 2,290 0.66 8.9 0.646 5.9 126    PBNB.sub.2/3 Mg.sub.1/3      O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3 9 40.0 34.48    850 1,200 100      16.8 8.82 --  .sub.2/3  25       4+10 200 40 1671 0.84 -- 0.67 5.22 293        PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3 10      35.0 33.74    2.61 28.65 -- " " " 1,140 2.45 -- 0.51 2.9 294 11 35.0      38.42 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3      MnO.sub.2 850 1160 90    23.40 3.18 3.8 4+10 .sub.2/3  30        200 30      506 0.24 0.75 0.446 1.58 1,070 12 45 39.54 PBNB.sub.2/3 Zn.sub.1/3      O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3  850 1240 100    5.44 10.02 --      4+10 .sub.2/3  25        200 30.0 1.000 0.64 1.7 0.562 3.02 1,500 13      42.5 39.73 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3      O.sub. 3    13.29 4.48 -- " " " 1,310 0.24 1.0 0.577 3.65 1,106 14 42.5      44.56 PBNB.sub.2/3 Co.sub.1/3 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3      850 1,170 180       4+10 .sub.2/3  40    8.45 4.49 --  200 35.0 1,340      0.28 1.5 0.646 4.34 1,003 15 42.5 33.29 PBNB.sub.2/3 Co.sub.1/3 O.sub.3      PBNB.sub.2/3 Mn.sub.1/3 O.sub.3    19.72 4.49 -- " " " 1,500 0.28 1.75      0.529 3.5 794 16 35.0 28.34 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 PBNB.sub.2/3      Ni.sub.1/3 O.sub.3  850 1,190 140        2/3 40 3,739 1.8 -- 0.642 7.67      67    9.36 27.3 -- 4 + 10 200 35.0 17 42.5 39.16 PBNB.sub.2/3 Mg.sub.1/3      O.sub.3 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3    8.29 10.05 -- " " " 3130 1.41      -- 0.677 7.8 72 18 35.0 28.34 PBNB.sub.2/3 Mg.sub.1/3       O.sub.3 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3 MnO.sub.2 850 1,160 100       4      + 10 2/3 30    9.36 27.3 1.9  200 40.0 1,740 0.57 1.8 0.565 4.12 475 19      42.5 43.82 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3 PBNB.sub.2/3 Co.sub.1/3      O.sub.3 -- 850 1,180 140       4 + 10 2/3 25    10.06 3.62   200 30.0      830 0.78 -- 0.6 3.06 574 20 35.0 28.34 27.3 9.36 -- " " " 2,699 1.98 8.1      0.656 6.44 248    PBNB.sub.2/3 Ni.sub.1/3 O.sub.3 PBNB.sub.2/3       Co.sub.1/3 O.sub.3 21 42.5 43.82 PBNB.sub.1/2 Ni.sub.1/3 O.sub.3      PBNB.sub.2/3 Co.sub.1/3 O.sub.3 MnO.sub.2 850 1,150 100    10.06 3.62      3.8 4 + 10 2/3 45 454 0.57 0.95 0.425 6.42 1,030        200 35.0 22 40.0      39.48 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3      800 1,140 140        .sub.2/3  30 2.555 1.49 -- 0.658 6.72 56    6.66      13.86 -- 4 + 10 200 30.0 23 35.0 37.05 PBW.sub.1/2 Zn.sub.1/2 O.sub.3      PBNB.sub.2/3 Zn.sub.1/3 O.sub.3    15.09 12.86 -- " " " 1,465 2.27 --      0.64 4.66 71 24 37.5 35.63 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBNB.sub.2/3      Zn.sub.1/3 O.sub.3 MnO.sub.2 800 1,150 90        .sub.2/3  30 1,590 0.57      1.4 0.587 4.25 510    14.51 12.36 1.9 4 + 10 200 30.0 25 37.5 40.0      PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3 -- 800      1,140 100       4 + 10 2/3 25 2,239 0.96 -- 0.616 2,762 759    13.73      8.77   200 30.0 26 40.0 33.18 PBW.sub.1/2       Zn.sub.1/2 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3  800 1,140 100 2,133      2.26 -- 0.64 5.53 280    6.66 20.16  4 + 10 2/3 25        200 30.0 27 "      " " " MnO.sub.2 800 1,145 100       4 + 10 2/3 30 2,420 0.5 6.7 0.593      5.47 360      0.77  200 40.0 28 42.5 42.66 PBW.sub.1/2 Zn.sub.1/2      O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3  800 1,145 100       4 + 10 2/3      30    6.38 8.46 "  200 40.0 1,370 0.36 2.5 0.572 3.84 430 29 40.0 39.48      PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3  800      1,160 140        2/3 30    6.66 13.86 -- 4 + 10 200 30.0 2,762 1.35 --      0.703 7.65 67 30 37.5 41.13 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub. 2/3      Zn.sub.1/3 O.sub.3    6.94 14.43 -- " " " 827 1.95 -- 0.564 2.89 114 31      40.0 39.48 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub..sub.2/3 Zn.sub.1/3      O.sub.3   1,130 90        2/3 35 2,100 0.29 2.2 0.595 4.97 390    6.66      13.86 0.76 " 200 30.0 32 42.5 37.37 12.88 7.25 -- " 1,140 140      .sub.2/3  30 2,973 1.04 " 0.618 6.23 434    PBW.sub.1/2 MG.sub.1/2      O.sub.3 PBNB.sub.2/3 CO.sub.1/3 O.sub.3   200 30.0 33 35.0 33.15      PBW.sub.1/2 MG.sub.1/2 O.sub.3 PBNB.sub.2/3 CO.sub.1/3 O.sub.3    14.02      17.83 -- " " " 1,268 1.97 -- 0.533 3.29 492 34 42.5 41.05 PBW.sub.1/2      MG.sub.1/2 O.sub.3 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3   1,170 140      2/3 30 6.39 10.06 -- " 200 2.01,6661.16 2.74 0.61 4.6820035 37.535.06PBW.      sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub. 2/3 Ni.sub.1/3 O.sub.3    16.19      11.25 -- " " " 1,128 1.83 -- 0.568 3.45 140 36 40.0 36.6 PBW1/2       Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3 MnO.sub.2  1.140 140          2/3 35    13.10 10.3 0.76  200 32.0 2,180 0.15 7,750 0.643 5.76 230      37 42.5 38.12 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3      O.sub.3   1.200 100        2/3 30    4.48 14.9 -- " 200 30.0 1,890 0.5      2.4 0.615 49.4 193 38 45.0 36.46 PBW.sub.1/2 Mg.sub.1/2       O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3 -- " " " 1,885 0.6 1.6 0.54      4.04 510    4.29 14.25 39 40.0 37.8 PBW.sub.1/2 Mg.sub.1/2 O.sub.3      PBW.sub.1/2 Zn.sub.1/2 O.sub.3 -- " 1,100 140 2,634 1.54 -- 0.675 7.06      88    6.66 15.54   2/3 30 200 30.0 40 37.5 39.37 PBW.sub.1/2 Mg.sub.1/2      O.sub.3 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 -- " " " 989 1.76 -- 0.565 3.18      107    6.94 16.19 41 40.0 41.46 PBW.sub.1/2 Ni.sub.1/2       O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3--8001.140140 1.4701.86 --      0.6154.76205  4.68 13.86  4+10 2/3 30        200 30.0 42 42.5 39.73      PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 -- " " "      2,480 1.2 -- 0.613 5.92 83    4.48 13.29 43 42.5 39.73 PBW.sub.1/2      Ni.sub.1/2 O.sub.3 PBNB.sub.2/3 Zn.sub.1/3 O.sub.3 MnO.sub.2 800 1,145      90 2,280 0.42 4.1 0.65 5.91 75    4.48 13.29 0.76 4+10 2/3 40        200      32.0 44 37.5 31.25 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 PBW.sub.1/2       Ni.sub.1/2 O.sub.3 -- 850 1,100 100 3,468 2.65 -- 0.668 7.88 63      18.75 12.5  4+10 2/3 30        200 35.0 45 40.0 30.0 PBW.sub.1/2      Ni.sub.1/2 O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " " " 4,197 1.6 --      0.633 7.96 78    12.0 18.0    PBW.sub.1/2 Ni.sub.1/2       O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 MnO.sub.2 46 42.5 40.14 10.46      6.9 1.9 800 1,130 90 1,890 0.62 2.5 0.602 4.88 0       4+10 2/3 30       200 30.0 47 37.5 40.13 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.2/3      Mg.sub.1/3 O.sub.3 MnO.sub.2 " " " 550 0.42 1.6 0.484 1.82 950    4.88      17.49 3.8 48 40.0 36.6 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.2/3      Co.sub.1/3 O.sub.3 -- " 1,470 140 3,009 1.48 -- 0.637 6.73 89    11.94      11.46   2/3 35        200 35.0 49 42.5 40.54 PBW.sub.1/2 Ni.sub.1/2      O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3 -- 800 1.170 140 2,270 0.34 3.1      0.639 5.65 679    12.48 4.48  4+10 2/3 35        200 30.0 50 40.0 43.50      PBW.sub.1/2 Ni.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3 -- " " "      501 0.56 1.4 0.518 1.86 1725    5.58 10.92 51 37.5 30.44 PBNB.sub.1/2      Ni.sub.1/3 O.sub.3 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 -- " " 140 2,360 1.9      -- 0.655 6.14 66    26.25 5.81    35         35.0 52 42.5 34.67 PBNB.sub.      2/3 Ni.sub.1/3 O.sub.3 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 -- " " " 2.142      1.38 -- 0.652 5.86 93    10.35 12.48 53 37.5 30.44 PBNB.sub.2/3       Ni.sub.1/3 O.sub.3 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 MnO.sub.2 " 1,140 90      1,520 0.45 2.35 0.525 3.54 770    26.25 5.81 1.9  2/3 45 20030.0 54 42.5      37.26 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBW.sub.1/2 Ni.sub.1/2 O.sub.3 -- "      1,120 80 2,310 0.72 -- 0.584 5.01 172   14.9 5.34   2/3 40        200      35.0 55 37.5 40.5 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBW.sub.1/2 Ni.sub.1/2      O.sub.3 -- " " " 1,120 1.55 -- 0.5 2.94 188    16.18 5.82 56 37.5 35.0      PBW.sub.1/2 Co.sub.1/2 O.sub.3 PBNB.sub.2/3 Co.sub.1/3 O.sub.3 -- "      1,135 80 3,368 5.03 -- 0.622 6.65 198    9.62 17.88   2/3 25        200      20.0 57 40.0 35.34 PBW.sub.1/2 Co.sub.1/2 O.sub.3 PBNB.sub.2/3       Co.sub.1/3 O.sub.3 -- " " " 2,548 0.69 -- 0.608 5.61 147    4.5 20.16      58 42.5 38.29 PBW.sub.1/2 Mg.sub.1/2 O.sub.3 PBW.sub.1/2 Co.sub.1/2      O.sub.3 -- " 1,150 80 2,390 2.09 -- 0.605 5.42 250    14.89 4.32   2/3      25        200 30.0 59 42.5 40.71 PBW.sub.1/2 Ni.sub.1/2       O.sub.3 PBW.sub.1/2 Co.sub.1/2 O.sub.3 -- " " 90 2,387 1.4 -- 0.633      5.84 232    4.31 12.48    25         30.0 60 45.0 38.94 PBW.sub.1/2      Ni.sub.1/2 O.sub.3 PBW.sub.1/2 Co.sub.1/2 O.sub.3 -- " " " 1,986 1.17 --      0.504 3.96 3.66    4.12 11.94 61 45.0 35.31 PBW.sub.1/2 Ni.sub.1/2      O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " 1.150 120 1,423 0.25 --      0.519 3.44 538    14.25 5.44   2/3 30        200 30.0 62 40.0 38.4      PBW.sub.1/2 Co.sub.1/2 O.sub.3 PBNB.sub.1/2 Zn.sub.1/3 O.sub.3 -- "      1,140 90 1,435 1.05 -- 0.623 4.34 424    13.13 8.42   2/3 25        200      30.0 63 37.5 42.37 PBW.sub.1/2 Co.sub.1/2 O.sub.3 PBNB.sub.2/3       Zn.sub.1/3 O.sub.3 -- " " " 1,032 0.46 -- 0.614 3.6 307    16.19 3.94      64 40.0 41.46 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBNB.sub.2/3 Ni.sub.1/3      O.sub.3 -- " " 100 1,470 1.86 -- 0.615 4.76 205    4.68 13.86    30         35.0 65 37.5 44.94 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBNB.sub.2/3      Ni.sub.1/3 O.sub.3 -- " " " 1,072 1.76 -- 0.566 3.28 142    11.38 6.18      66 40.0 36.6 PBNB.sub.2/3 Ni.sub.1/3 O.sub.3 PBW.sub.1/2 Co.sub.1/2      O.sub.3 -- " 1,170 140 3,009 1.48 -- 0.637 6.73 89    11.46 11.94   2/3      35        200 35.0 67 42.5 42.66 PBW.sub.1/2 Co.sub.1/2       O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " 1,140 100 1,633 1.89 --      0.55 4.72 266        200 30.0 68 40.0 39.0 PBW.sub.1/2 Co.sub.1/2      O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " " " 750 0.62 -- 0.555 2.59      605    13.44 7.56 69 42.5 37.26 PBW.sub.1/2 Ni.sub.1/2       O.sub.3 PBW.sub.1/2 Zn.sub.1/2 O.sub.3 -- " " " 2,376 1.28 -- 0.533      4.76 90    5.34 14.9 70 42.5 38.52 PBW.sub.1/2 Co.sub.1/2 O.sub.3      PBNB.sub.2/3 Mn.sub.1/3 O.sub.3 -- " 1,170 140 1,650 0.84 2.3 0.512 3.53      1.065        2/3 35    9.10 9.88   200 35.0 71 40.0 42.42 PBW.sub.1/2      Zn.sub.1/2 O.sub.3 PBNB.sub.2/3 Mn.sub.1/3 O.sub.3 -- " " " 555 0.62      1.75 0.507 2.0 1.292    6.66 10.92 72 40.0 39.96 PBW.sub.1/2 Zn.sub.1/2      O.sub.3 PBW.sub.1/2 Co.sub.˜ O.sub.3 -- " 1,180 140 2,376 0.59 --      0.567 4.99 320    15.54 4.5   2/3 30        200 35.0 73 42.5 38.29      PBW.sub.1/2 Zn.sub.1/2 O.sub.3 PBW.sub.1/2 Co.sub.1/2 O.sub.3 -- " " "      792 1.04 -- 0.56 2.78 569    14.9 4.31 74 40.0 35.82 PBW.sub.1/2      Mg.sub.1/2 O.sub.3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " " " 1,269 2.38      -- 0.562 3.58 112    15.54 8.64 75 42.5 34.33 PBW.sub.1/2 Mg.sub.1/2 O      hd 3 PBNB.sub.2/3 Mg.sub.1/3 O.sub.3 -- " " 2,805 1.58 -- 0.51 5.1 100       14.89 8.28      Note:      (4+10 hours)  duration of synthesis: first  4 hours; second  10 hours. 

What is claimed is:
 1. A piezoceramic material consisting essentially of, in molar percent:PbTiO₃ --40 PbZrO₃ --35.40 PbW_(1/2) Ni_(1/2) O₃ --9.84 PbNb_(2/3) Mg_(1/3) O₃ --14.76.
 2. A piezoceramic material consisting essentially of, in molar percent:PbTiO₃ --38.75 PbZrO₃ --30.62 PbW_(1/2) Ni_(1/2) O₃ --12.25 PbNb_(2/3) Mg_(1/3) O₃ --18.37.
 3. The piezoceramic material as claimed in claim 2, containing, as a modifying oxide, 0.76 mol.% of MnO₂.
 4. A piezoceramic material consisting essentially of, in molar percent:PbTiO₃ --37.5 PbZrO₃ --31.25 PbW_(1/2) Ni_(1/2) O₃ --12.5 PbNb_(2/3) Mg_(1/3) O₃ --18.75.
 5. A piezoceramic material consisting essentially of, in molar percent:PbTiO₃ --40.0 PbZrO₃ --30.0 PbW_(1/2) Ni_(1/2) O₃ --12.0 PbNb_(2/3) Mg_(1/3) O₃ --18.0. 